Images Dated 4th October 2016

Thyroid, LM

Thyroid gland. Light micrograph (LM) of a thyroid gland showing the follicles. The follicles are lined by a single layer of cuboidal epithelial cells (blue), which synthesise and secrete the iodine-containing hormones T3 (tri-iodothyronine) and T4 (thyroxine). The thyroid follicle is filled with a glycoprotein substance called thyroglobulin or thyroid colloid (blue green), which is a storage form of the thyroid hormones. When actively secreting hormones the lining cells are large and cuboidal, when less active the follicles are distended and the secretory cells flattened. Magnification: x800 when printed 10cm wide

© Science Photo Library

Valley of Little Missouri River and sedimentary hills in North Unit of Theodore Roosevelt National Park, North Dakota, USA

Theodore Roosevelt National Park is a United States National Park comprising three geographically separated areas of badlands in western North Dakota. The park was named for U.S. President Theodore Roosevelt. The park covers 70, 446 acres of land in three sections: the North Unit, the South Unit, and the Elkhorn Ranch Unit. The parks larger South Unit lies alongside Interstate 94 near Medora, North Dakota. The smaller North Unit is situated about 80 mi (130 km) north of the South Unit, on U.S. Highway 85, just south of Watford City, North Dakota. Roosevelts Elkhorn Ranch is located between the North and South units, approximately 20 mi (32 km) west of US 85 and Fairfield, North Dakota. The Little Missouri River flows through all three units of the park. The Maah Daah Hey Trail connects all three units

© John Barger / DanitaDelimont.com

Gunnison River winding through Black Canyon, Colorado, USA

Black Canyon of the Gunnison National Park is a United States National Park located in western Colorado and managed by the National Park Service. There are two primary entrances to the park: the south rim entrance is located 24 km east of Montrose, while the north rim entrance is 18 km south of Crawford and is closed in the winter. The park contains 19 km of the 77 km long Black Canyon of the Gunnison River. The national park itself contains the deepest and most dramatic section of the canyon, but the canyon continues upstream into Curecanti National Recreation Area and downstream into Gunnison Gorge National Conservation Area

© Howie Garber / Danita Delimont